def is_lambda_error_response()

in samcli/local/services/base_local_service.py [0:0]

• 21 lines of code
• 12 McCabe index (conditional complexity)

    def is_lambda_error_response(lambda_response):
        """
        Check to see if the output from the container is in the form of an Error/Exception from the Lambda invoke

        Parameters
        ----------
        lambda_response str
            The response the container returned

        Returns
        -------
        bool
            True if the output matches the Error/Exception Dictionary otherwise False
        """
        is_lambda_user_error_response = False
        lambda_response_error_dict_len = 2
        lambda_response_error_with_stacktrace_dict_len = 3

        try:
            lambda_response_dict = json.loads(lambda_response)

            # This is a best effort attempt to determine if the output (lambda_response) from the container was an
            # Error/Exception that was raised/returned/thrown from the container. To ensure minimal false positives in
            # this checking, we check for all the keys that can occur in Lambda raised/thrown/returned an
            # Error/Exception. This still risks false positives when the data returned matches exactly a dictionary with
            # the keys 'errorMessage', 'errorType', 'stackTrace' and 'cause'.
            # This also accounts for a situation where there are three keys returned, two of which are
            # 'errorMessage' and 'errorType', for languages with different error signatures
            if (
                isinstance(lambda_response_dict, dict)
                and len(lambda_response_dict.keys() & {"errorMessage", "errorType"}) == lambda_response_error_dict_len
                and (
                    (
                        len(lambda_response_dict.keys() & {"errorMessage", "errorType", "stackTrace", "cause"})
                        == len(lambda_response_dict)
                    )
                    or (len(lambda_response_dict) == lambda_response_error_with_stacktrace_dict_len)
                )
            ):
                is_lambda_user_error_response = True
        except ValueError:
            # If you can't serialize the output into a dict, then do nothing
            pass
        return is_lambda_user_error_response